#! /bin/sh
# $Id: forwedit 0.5 1996/09/14 05:30:16 jerry Exp $
#
###	forwedit - editor for MH forw command; makes Subject same as original msg
###	Usage (in MH profile):
###		forw: -editor forwedit
###	optional, name an editor to use after this script: default is prompter(1):
###		forwedit-next: someeditor
##
##	forwedit sets the Subject: header field of your draft forwarded message
##	to be the same as the subject of the original message with (fwd) after.
##	If you forward more than one message, it uses "Forwarded messages".
##	(You can configure this by setting the $draftsubj shell variable.)
##
##	After doing that, forwedit calls an editor for you to compose the draft
##	header and body; it tries the MH profile entries "forwedit-next:" and
##	"Editor:", then the environment variables VISUAL and EDITOR.  The
##	default editor is prompter(1).
#
#	Note: there are calls to external utilities in here that could be
#	replaced with hardcoded values to speed up execution on slow systems:
#	"echo a | /bin/tr" and two calls to $mhdir/mhparam.
#	If you have an older MH, you won't have mhparam(1); use the "mhprofile"
#	script from "MH & xmh" Nutshell Handbook instead... or hardcode an editor.
#
#	Tabstops in this code are set at 4 (in vi, use ":se ts=4 sw=4").
#
# 	Thanx to David Goodwin and Dan Eisenbud for bug reports and patches.
#
#	USE AT YOUR OWN RISK.  SEEMS TO WORK, BUT IT'S YOUR RESPONSIBILITY!
#	Please tell me about bugs and fixes: Jerry Peek <jpeek@jpeek.com>

# Note: $draftsubj is set toward middle of script; configure if you want
mhdir=/usr/local/mh		# Where MH binaries like mhparam live
msgedit=/bin/ed			# For editing draft header
myname=forwedit			# Name of this program (HARDCODED for speed)
#myname=`basename $0`	# Name of this program (USE THIS if script has links)
showbad="/bin/cat -v"	# Command to show non-printable characters

case $# in
1)	draft="$1"
	if [ ! -r "$draft" -o ! -w "$draft" -o ! -s "$draft" ]; then
		echo "$myname aborting: can't read/write draft '$draft'" 1>&2
		exit 1
	fi
	;;
*)	echo "$myname aborting: I need one command line argument; I got $#:
	'$*'" 1>&2
	exit 1
	;;
esac

# Scan message number(s) from $mhmessages environment variable
# (only set with "forw -annotate"; else we scan cur).  Store subject(s).
# If multiple messages, $mhmessages can look like "1-5 23"; let scan(1)
# break those up.
origsubj=`$mhdir/scan -width 1000 -format '%{subject}' ${mhmessages-cur}` || {
	echo "$myname aborting: 'scan ${mhmessages-cur}' failed?" 1>&2
	exit 1
}

# Get subject for forwarded message draft.
# If $origsubj contains a newline, there were multiple messages (and
# "forw -annotate" was used... no way to get this info without -annotate).
# If subject already has "(fwd)", don't add another.
# (To get fancier here, use expr(1) or echo|sed to customize subject.)
case "$origsubj" in
*"
"*)	draftsubj="Forwarded messages" ;;
*"(fwd)"*)	draftsubj="$origsubj" ;;
*)	draftsubj="$origsubj (fwd)" ;;
esac

# Edit draft by finding first Subject: line and gluing in $draftsubj.
# This works because ed(1) starts at end of draft; search will wrap
# forward to start of draft and find Subject: in draft header.
#
# ed(1) should be silent.  If it returns any errors, complain and quit.
# Note: ed(1) can bomb on really big messages.
# If this is a problem, replace with sed(1) and a temporary file.
#
# Start by storing a control-A character in $A.  This makes a delimiter
# for ed that's almost surely not in $draftsubj (else, ed could bomb).
# Using echo and tr means we don't have to hardcode a control character here:
A=`echo a | /bin/tr a '\001'`
scmd="/^[Ss]ubject:/s${A}\$${A}$draftsubj${A}"	# substitute command for ed(1)
# echo $scmd, a newline, and a "w" (write) command to ed(1);
# save stderr and stdout, if any, in $edout:
edout=`echo "$scmd
w" | $msgedit - $draft 2>&1`
# Test exit status ($?) and ed output ($edout); should be 0 and empty.
# If so, edit draft.  Else, complain and show editing command we tried:
case "$?$edout" in
0"")
	# Find editor to use on draft (default: prompter(1)) and run it:
	editor=`$mhdir/mhparam "$myname-next" || $mhdir/mhparam editor`
	editor=${editor:-${VISUAL-${EDITOR-$mhdir/prompter}}}
	exec $editor "$draft"	# Save a process by execing editor
	# Always an error if we get here:  exec failed.
	echo "$myname aborting: 'exec $editor $draft' failed" 1>&2
	exit 1
	;;
*)	# non-zero exit status or ed output.  Complain and quit:
	echo "$myname: '$msgedit - $draft' failed with editor command:
	$scmd" | $showbad 1>&2
	echo "Output, if any, was:
	$edout" 1>&2
	exit 1
	;;
esac